1. Field of the Invention
The invention relates in general to the interrelationship between complex speaker edges and especially configured resonator panels wherein speakers with high aspect ratio ribbed resonator plates are mounted to supporting frames through complex speaker edges. Embodiments include complex speaker edges with non-uniform vibration damping profiles or characteristics around their peripheries, and resonator plates with non-axially aligned ribs. In this field, the quality of the emitted sound is optimized, for example, by matching the vibration damping profile and the angle at which the ribs extend.
2. Description of the Prior Art
Speaker edges composed of various flexible materials had been widely employed in the mounting of acoustic vibration plates, particularly conical shaped vibration plates, to supporting housings or frames. See, for example, Okamura et al. U.S. Pat. No. 3,980,841, and Tabata et al. U.S. Pat. No. 6,680,430. Typically, the prior proposed speaker edges had been round and deployed on the edges of conical resonator plates.
It is well known that speaker edges substantially improve the characteristics of the sound that is generated by a speaker. It had been proposed to construct speaker edges from various flexible materials including, for example, cloth, foamed rubber, foamed urethane, compressed foamed urethane, other flexible thermoplastic and thermosetting materials, and the like. Tabata et al. teaches that speaker edges made from thermally compressed foam are not satisfactory because, inter alia, the densities of the compressed foam speaker edges supposedly vary randomly. Talbata et al. teaches that longitudinal uniformity is necessary throughout a foamed speaker edge. Talbata et al allegedly achieves longitudinal uniformity by foaming the material of construction for the speaker edges in situ, rather than by compressing pre-formed foam blocks.
Rectangular planar resonator plates with high aspect ratios for use in flat elongated speaker assemblies had been described previously. See Yanagawa et al. U.S. Pat. No. 6,687,381. Flat speaker assemblies are configured to fit into small generally narrow spaces. Such flat speaker assemblies generally employ flat resonator panels in place of the large speaker cones that are typically found in more bulky speaker assemblies. The flat resonator panels are typically elongated so that they have high aspect ratios.
Speakers containing high aspect ratio planar resonator plates had presented problems in achieving the desired sound quality. While not wishing to be bound by any theory, this is believed to be at least partly due to the existence of undesirable standing waves in the resonator plates. It is believed that these standing waves cause cancellation of the desired sound waves. The existence of such cancellation or interference is detectable by measuring the sound pressure levels of the acoustic output from the speaker assembly over the range of frequencies that are detectable by the human ear. It is generally desired by the art that a speaker assembly generate a curve of frequency versus sound pressure level that is as flat as possible. That is, in the desired condition this curve exhibits approximately a constant sound pressure level between approximately 20 and 20,000 Hertz. It is inevitable that this curve will fluctuate somewhat from the average. The art recognizes that the magnitude of the excursions in this curve from the average sound pressure level should be as small as possible. As is well known to those in the art, various well recognized standards have been promulgated and now exist for measuring such acoustic output. Such standards generally vary from jurisdiction to jurisdiction, as is well understood by those skilled in the art, but typically require the use of a microphone spaced a set distance, for example, one meter, from the speaker that is being tested.
The problems encountered in achieving the desired sound quality had generally limited the usage of high aspect ratio planar resonator plates. As noted, for example, by Okamura et al. U.S. Pat. No. 3,980,841, tuning a speaker to get the desired quality of sound is often a delicate matter. Insofar as possible, the characteristics of a speaker edge should not be so sensitive to variations in materials and dimensions that manufacturing tolerances become prohibitively expensive to control.
Various resonator plates or diaphragms of different constructions had been previously suggested. Anisotropic rectangular and elliptical diaphragms constructed with double-skins spaced apart by parallel walls extending between the skins had been previously proposed. See, for example, Lock et al. U.S. Pat. No. 6,411,723. According to Lock et al., the walls extend longitudinally so that the longitudinal bending strength is greater than the transverse bending strength. There is no teaching or suggestion as to any orientation of the walls other than parallel or transverse to the edges of the diaphragm, or that there would be any advantage to orienting the walls at any other angle.
Elongated resonator panels with resonance inhibiting layers in the edge region in the major-axis direction had been proposed. See Takahashi Publication No. US 2004/0026164, published Feb. 12, 2004.
Attempts to solve these problems were generally unsuccessful. An individual with a well trained ear could generally detect that the sound emitted by prior art devices was of a quality that was inferior to that of the original source, particularly for musical performances. Instruments were generally inadequate to identify and quantify the exact nature of the inferior quality. Those concerned with these problems recognize the need for an improvement.
These and other difficulties of the prior art have been overcome according to the present invention.